1. Field of the Invention
The present invention relates to a method for evaluating artificial receptors, more particularly an evaluation method for use in development of artificial receptors, which have been recently growing in use as separating agents for chemicals, sensor materials for chemicals, reagents for immunoassays and the like.
2. Description of Related Art
In living bodies, a variety of functions are expressed by proper recognition of a huge amount of chemical substances. For example, an enzyme effectively catalyzes a chemical reaction in a living body by recognizing a specific substance. Also various kinds of receptors existing in cell membranes bind selectively to specific substances and transfer extracellular information received from the specific substances into cells. The cells in turn exercise functions required in a living body such as suppression, regulation and the like on the basis of the extracellular information.
Artificial receptors are those artificially designed and synthesized to imitate such receptors and exhibit good molecular recognition functions. For designing and synthesizing such artificial receptors, there are proposed several methods, among which "Molecular Imprinting method by Wuff, G., Angew.Chem.,Int.Ed.Engl.,34,1812-1832(1995) is said to be particularly excellent and preferable.
According to the Molecular Imprinting method (hereinafter referred to as MI method), an artificial polymeric receptor can be prepared by polymerizing a polymerizable organic compound (a functional monomer) which interacts with a template substance (also referred to as a key molecule, imprint molecule or template molecule) and a crosslinker(i.e., crosslinking monomer) in the presence of the template substance and then releasing and removing the template substance from the resultant polymer. This polymeric receptor is a polymer characterized by having a cavity fit to the molecular morphology and size of the template substance. In addition to that, the polymer obtained by the MI method (hereinafter referred to as a molecularly imprinted polymer) is physically and chemically stable and has an excellent storage endurance.
Published Japanese Patent Application No. HEI 8(1996)-506320 (corresponding to the International Patent Application Publication No. WO94/11403) discloses the use of a molecularly imprinted polymer (artificial antibody) for detecting an antigen in immunoassay.
Further, Japanese Unexamined Patent Publication No. HEI 8(1996)-15160 discloses a biomimetic sensor using a thin molecularly imprinted polymer.
With a view to obtaining a suitable molecularly imprinted polymer, however, the MI method has several problems. First, it is necessary to study suitable polymerization conditions about combination and proportion of components, i.e., the functional monomer and crosslinker, with respect to the template substance as well as a solvent to be used for polymerization. Moreover, in order to evaluate the obtained molecularly imprinted polymer, the polymer must be crushed into pieces, packed in a column and evaluated about to what extent the polymer can recognize the template substance. This whole evaluation process consumes considerable time and labor.
A conventional in situ method by J. Matsui, T. Kato, T. Takeuchi, M. Suzuki, K. Yokoyama, E. Tamiya, and I. Karube, Anal.Chem., 65, 2223(1993), which was developed for reducing such time and labor, discloses a method for preparing a molecularly imprinted polymer directly in a column for HPLC by feeding a mixture of a template substance, functional monomer(s), a crosslinker, a solvent, an initiator for polymerization and the like in the column and polymerizing in situ. According to this method, the ability of the molecularly imprinted polymer to recognize the template molecule can be evaluated only by connecting the resulting column to a pump for HPLC and subjecting to HPLC analysis. However, this method is not a satisfactory one because it still needs much time and work.